Abstract: A circle drive system with clutch protection in motor graders is disclosed. The circle drive system includes a hydraulic motor that is configured to receive a pressurized fluid and generate a torque for a rotation of a circle and a moldboard. The circle drive system also includes a gearbox to transfer the torque generated by the hydraulic motor to the circle. Further, the circle drive system includes a clutch connected to the hydraulic motor at one end and to the gearbox at another end. In addition, the circle drive system also includes a hydraulic circuit having a pressure relief valve to relieve the pressurized fluid supplied to the hydraulic motor when a pressure of the pressurized fluid exceeds a predefined threshold. The pressure relief valve thereby, limits the torque generated by the hydraulic motor to less than or equal to a torque capacity of the clutch.

Abstract: To provide a swing-type construction machine that can reduce force of working device pipes which is generated in accordance with swinging of a working device and presses against a side wall of a swing post.

Abstract: In a rotation control device for rotating a rotation motor at speed in accordance with a boom raising operation amount, at the time of a combined operation for simultaneously performing a rotation action and a boom raising action, a limitation value of rotation torque in accordance with the boom raising operation amount is determined by rotation torque limitation value setting means of a controller, the limitation value serving as a rotation torque limitation value is sent to rotation speed control means, and a command value of the rotation torque is torque-limited by rotation torque limiting means.

Abstract: A control-mode switching device includes: a plurality of actuators (2, 6, 7) that conduct different movement; driving means (10, 11, 12, 13, 14, 15) that drive the actuators; a plurality of control levers (22a-22c) that command operation of the driving means; a plurality of limit switches (72a-72e) that detect arrival of the control levers to the proximity of an end of a control range; a mode judging means (controller 23) that judges whether a priority operation mode is taken or not in accordance with a combination of on/off conditions of the limit switches; and a drive controlling means (controller 23) that, when it is judged by the mode judging means that the priority operation mode is taken, controls the driving means so that an output of selected one or more of the driving means becomes larger than that in a normal mode or the power ratio as compared with the other driving means becomes larger.

Abstract: Method and arrangement for controlling movements of a work vehicle. The positional or geometric state of an equipment assembly for handling objects or material is determined and the control scheme which governs operation of at least one driveline component of the vehicle is varied depending on the determined equipment assembly state.

Abstract: The invention relates to a cutter head for an excavator machine including at least one cutter motor, each cutter motor comprising: a fastener plate; a mounting structure secured to the fastener plate and presenting a central portion and two mounting assemblies disposed on either side of the fastener plate; two hydraulic motors mounted in said mounting assemblies; a shaft common to both hydraulic motors; a plurality of conduits formed in the thickness of said fastener plate for passing the flow of the liquid used by the hydraulic motors; and a plurality of ducts formed in said central portion of the mounting structure, said ducts being connected to said conduits and to said hydraulic motors to connect each of the two motors to each of said conduits.

Abstract: A hydraulic circuit of an excavating and slewing working vehicle of two pump system, wherein a directional control valve for slewing and a directional control valve for arm are tandem-connected to the upstream side and downstream side of the delivery oil passage of a second hydraulic pump, respectively, a directional control valve for bucket are connected to the delivery oil passage of a first hydraulic pump, and then a bleed switching valve connected, through a check valve between the directional control valve for slewing and the directional control valve for arm and switched to connect to or disconnect from a tank on the upstream side of the check valve and the directional control valve for slewing are operated interlockingly with each other.

Abstract: A hydraulic control circuit for a boom cylinder in a work machine, which, when controlling supply and discharge of pressurized oil with respect to a boom cylinder, improves fuel efficiency, work efficiency in combined operations, and improves work efficiency and operationality in the work of difficult boom operations, such as debris raking-up work and bumping work, wherein the hydraulic control circuit of a boom cylinder is provided with a change valve to hold a first boom control valve at a neutral position, a communication line for causing a head side oil chamber and a rod side oil chamber to communicate with each other, an opening valve for opening and closing the corresponding communication line, and pilot operating check valve that is changed to an unidirectional state where, although an oil flow from the head side oil chamber to the rod side oil chamber is permitted, a reverse flow is hindered, and to a bi-directional state where oil flows in both directions, and further a second boom control valve is p

Abstract: A skid steer vehicle with sprung suspensions is configured to lock the suspensions whenever the operator manipulates a manual control that generates a signal to move the loader arms or the bucket of the vehicle. The operator control, such as a joystick, sends a signal to an electronic controller indicating that the operator has moved the control and is thereby requesting the loader arms or bucket to move. The electronic controller responds to this signal by moving the loader arms or bucket and simultaneously locking the suspensions.

Abstract: A front loader using smaller capacity engine, due to energy recuperation, while utilizing the same capacity and decreasing fuel consumption and toxic exhaust bulk. The front loader uses energy recuperation both when excavating material and upon movement with simultaneous lift of a loaded bucket. The front loader uses energy recuperation irrespective of the type of transmission to the loader wheels. The front loader uses a single crank control, without throttle control, hydraulic distributor of bucket turn, hydraulic distributor of boom lift, and displacement volume of variable pump-motor working equipment.

Abstract: A wheel loader, having a higher acceleration and an energy-saving performance, as well as a higher traveling and working efficiency, includes: a traveling system, having an engine (1) as a driving power source; and a hydraulic working system, operated by receiving pressurized oil from a hydraulic pump (81, 82) having the engine (1) as a driving power source. The hydraulic pump can be a variable displacement hydraulic pump (81) or the combination of a fixed displacement pump (82) and an unloader valve (821). The displacement volume (V) of the variable displacement hydraulic pump (81) can be changed from a maximum (Vmax) to a minimum (Vmin) when the hydraulic working system is changed to be in a neutral (non-operating) condition (Wo). The useful output of the hydraulic pump (81,82) can be changed from a maximum (Vmax) to a minimum (Vmin) when a vehicle speed is greater than a specified vehicle speed, or the speed gear is changed from a low side speed gear to a high side speed gear.

Abstract: A pump failure alarm system which is provided in a hydraulic working machine comprising hydraulic pumps driven by a prime mover, delivery lines joining with one another into one common delivery line on the downstream side, check valves provided in the delivery lines upstream of a point where the delivery lines join with one another, a hydraulic cylinder driven by a hydraulic fluid introduced through the common delivery line, and a hydraulic reservoir. The pump failure alarm system comprises pressure sensors for detecting respective delivery pressures of the hydraulic pumps, bypass lines having one ends connected to the delivery lines at points upstream of the check valves and the other ends connected to the hydraulic reservoir, solenoid switching valves for opening and closing the associated bypass lines, an alarm display unit for giving an alarm in correspondence to each of the hydraulic pumps, and a controller.

Abstract: A control system for controlling quantity of hydraulic fluid of an excavator. The control system of this invention provides a method for controlling the quantity of the hydraulic fluid supplied to the swing motor in which in case of swinging operation for driving the swing motor in order to turn the upper frame with respect to the lower frame, the first hydraulic pump is automatically controlled by the controller in order to optimally output hydraulic fluid to timely correspond to starting of the practical swinging operation of the swing motor.